Shuttle safety - Some representative problems
Maintenance and flight safety problems of space shuttle
Pinkel, I. I.↗
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Shuttle-safety - Some representative problems
Space shuttle safety, discussing rocket engine durability, turbine life, flaw detection, radiation hazards, etc
Pinkel, I. I.↗
Experimental investigation of Mach 3 cruise heating simulations on a representative wing structure for flight loads measurement
Radiant heating experiments were performed in the laboratory on an instrumented multispar wing structure to investigate: (1) how accurately the structural temperatures of a Mach 3 cruise-flight profile could be simulated, (2) what the effects of the heating and heating inaccuracies would be on the responses of strain-gage bridges installed on the structure, and (3) how these responses would affect flight loads measurements. Test temperatures throughout the structure agreed well with temperatures calculated for a Mach 3 profile. In addition, temperatures produced by two identical tests were repeatable to less than + or -6 K deg. Thermally induced strain-gage-bridge responses were large enough to be detrimental to a high-speed flight loads program with a goal of establishing aerodynamic loads (exclusive of thermal loads). It was shown that heating simulation can be used effectively for thermal calibration (that is, to provide corrections for a high-temperature environment), and that thermal calibration may not be needed if the simulation data are used to carefully select bridges and load equations.
Fields, R. A.↗
Flight test of an automatic approach and landing concept for a simulated space shuttle represented by the NASA Convair 990 aircraft
Unpowered automatic approaches and landings were conducted to study navigation, guidance, and control problems associated with terminal area, approach, and landing operation for the space shuttle. A Convair 990 aircraft was equipped with a digital flight-control computer connected to the aircraft control systems and displays. The flight tests evaluated, from 11,300 m to touchdown, the performance of a navigation and guidance concept that utilized blended radio/inertial navigation with VOR, DME, and ILS as the ground radio navigation aids. The results from 36 automatic approaches and landings are analyzed. Preliminary results indicate that this concept may provide sufficient accuracy that automatic landing of the unpowered shuttle orbiter can be accomplished on a conventional size runway.
Smith, D. W.↗
Experimental and theoretical aerodynamic characteristics of representative hypersonic cruise configurations. Part 1. Lift and drag. Part 2. Stability and trim
Explore the source record for details and available documents.
Nelms, W. P.↗
Method of identifying clusters representing statistical dependencies in multivariate data
Approach is first to cluster and then to compute spatial boundaries for resulting clusters. Next step is to compute, from set of Monte Carlo samples obtained from scrambled data, estimates of probabilities of obtaining at least as many points within boundaries as were actually observed in original data.
Borucki, W. J.↗
Slow and fast motion of cracks in inelastic solids. Part 1: Slow growth of cracks in a rate sensitive tresca solid. Part 2: Dynamic crack represented by the Dugdale model
An extension is proposed of the classical theory of fracture to viscoelastic and elastic-plastic materials in which the plasticity effects are confined to a narrow band encompassing the crack front. It is suggested that the Griffith-Irwin criterion of fracture, which requires that the energy release rate computed for a given boundary value problem equals the critical threshold, ought to be replaced by a differential equation governing the slow growth of a crack prior to the onset of rapid propagation. A new term which enters the equation of motion in the dissipative media is proportional to the energy lost within the end sections of the crack, and thus reflects the extent of inelastic behavior of a solid. A concept of apparent surface energy is introduced to account for the geometry dependent and the rate dependent phenomena which influence toughness of an inelastic solid. Three hypotheses regarding the condition for fracture in the subcritical range of load are compared. These are: (1) constant fracture energy (Cherepanov), (2) constant opening displacement at instability (Morozov) and (3) final stretch criterion (Wnuk).
Wnuk, M. P.↗
A high subsonic speed wind tunnel investigation of winglets on a representative second-generation jet transport wing
The effects of winglets on the aerodynamic forces and moments, loads, and crossflow velocities behind the wing tip are discussed. The results of the investigation indicate that winglets significantly reduce the drag coefficient at lifting conditions. The experiments were conducted in an 8-foot transonic pressure tunnel at Mach numbers from 0.70 to 0.83 and over a lift coefficient range up to 0.65. A semispan model was used.
Flechner, S. G.↗
The effect of winglets on the static aerodynamic stability characteristics of a representative second generation jet transport model
A baseline wing and a version of the same wing fitted with winglets were tested. The longitudinal aerodynamic characteristics were determined through an angle-of-attack range from -1 deg to 10 deg at an angle of sideslip of 0 deg for Mach numbers of 0.750, 0.800, and 0.825. The lateral aerodynamic characteristics were determined through the same angle-of-attack range at fixed sideslip angles of 2.5 deg and 5 deg. Both configurations were investigated at Reynolds numbers of 13,000,000, per meter (4,000,000 per foot) and approximately 20,000,000 per meter (6,000,000 per foot). The winglet configuration showed slight increases over the baseline wing in static longitudinal and lateral aerodynamic stability throughout the test Mach number range for a model design lift coefficient of 0.53. Reynolds number variation had very little effect on stability.
Jacobs, P. F.↗
Aerodynamic drag reduction tests on a full-scale tractor-trailer combination and a representative box-shaped ground vehicle
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Steers, L. L.↗
On the use of Pade approximants to represent unsteady aerodynamic loads for arbitrarily small motions of wings
The general behavior of unsteady airloads in the frequency domain is explained. Based on this, a systematic procedure is described whereby the airloads, produced by completely arbitrary, small, time-dependent motions of a thin lifting surface in an airstream, can be predicted. This scheme employs as raw materials any of the unsteady linearized theories that have been mechanized for simple harmonic oscillations. Each desired aerodynamic transfer function is approximated by means of an appropriate Pade approximant, that is, a rational function of finite degree polynomials in the Laplace transform variable. Although these approximations have many uses, they are proving especially valuable in the design of automatic control systems intended to modify aeroelastic behavior.
Vepa, R.↗
US metric study mission to the United Kingdom and the Federal Republic of Germany: Report of the NASA representative (Full Report)
For abstract, see preceding accession.
Vlannes, P. N.↗
Building application of solar energy. Study no. 2: Representative buildings for solar energy performance analysis and market penetration
The following topics are discussed: (1) Assignment of population to microclimatic zones; (2) specifications of the mix of buildings in the SCE territory; (3) specification of four typical buildings for thermal analysis and market penetration studies; (4) identification of the materials and energy conserving characteristics of these typical buildings; (5) specifications of the HVAC functions used in each typical building, and determination of the HVAC systems used in each building; and (6) identification of the type of fuel used in each building.
Hirshberg, A. S.↗
Solar power satellite. System definition study. Part 1, volume 5: SPS transportation. Representative system descriptions
Both LEO transportation (earth to low earth orbit) and GEO transportation (low earth orbit to geosynchronous orbit) segments were addressed. LEO options include both a 2 stage winged space freighter vehicle and a 2 stage ballistic recoverable vehicle. Both incorporate LO(2)/RP-1/LH(2) engines on the booster and standard SSME's on the upper stage. The orbit transfer vehicle options included chemical for geosynchronous satellite assembly and self powered electric propulsion for low earth orbit satellite assembly. An exhaust products analysis was conducted for the earth to LEO vehicle since atmospheric pollution could be a concern.
Source record↗
Vibration characteristics of walls and a plate glass window representative of those of a wood-frame house
Mechanical excitation was used, and measurements of acceleration response, natural frequencies, and nodal patterns were performed. Results indicate that the wall sections and the complete wall did not act as a unit in responding to sinusoidal vibration inputs. Calculated frequencies of the components that account for this independent behavior of the studs and face sheets agreed resonably well with experimental frequencies. Experimental vibrations of the plate glass window agreed with the calculated behavior, and responses of the window exposed to airplane flyover noise were readily correlated with the test results.
Carden, H. D.↗
The Snake River Plain, Idaho - Representative of a new category of volcanism
Studies of the volcanic geology of the Snake River Plain, Idaho, and comparison with other basaltic regions suggest a new category of volcanic activity, termed basaltic plains volcanism. Typified by the Snake River Plain, this style of volcanism is intermediate between basaltic flood (or plateau) eruptions and Hawaiian volcanism. Characteristics that are common to both Hawaiian and plains volcanism are: multiple lava flow units which erupt primarily from point sources, formation of low shields, and frequent emplacement through lava tubes or channels. Characteristics that are common to both flood basalts and plains volcanism are: high volume flows, vents aligned along rift zones, and planar surfaces. The recognition of plains volcanism in other areas provides a means to interpret the style of eruption and volcanic history.
Greeley, R.↗
Servicing costs for representative service missions
User cost for three satellite services were assessed. The three missions are: advanced X-ray astrophysics facility (AXAF) revisit; upper atmosphere research satellite (UARS) revisit: and solar maximum mission (SMM) Earth return. Service scenarios for the missions to identify service equipment needs and on orbit usage were developed. The AXAF revisit is a service mission involving a contamination sensitive satellite. Following servicing and checkout, the spacecraft is redeployed from the orbiter. The total user charges for revisit missions is from 5 to 10% less than the cost to build and relaunch a replacement satellite. It is indicated that satellite servicing from the Orbiter is cost effective.
Mockovciak, J., Jr.↗
Development of a simplified analytical method for representing material cyclic response
Development of a simplified method for estimating structural inelastic stress and strain response to cyclic thermal loading is presented. The method assumes that high temperature structural response is the sum of time independent plastic and time dependent elastic/creep components. The local structural stress and strain response predicted by linear elastic analysis is modified by the simplified method to predict the inelastic response. The results with simulations by a nonlinear finite element analysis and used time independent plasticity and unified time dependent material model are compared.
Moreno, V.↗